The invention relates to data recording devices; and, more particularly, to the program editing and selection of digitally encoded data tracks in a sequential medium such as magnetic tape.
Digitally encoded data is stored in a variety of media with modern electronic equipment including solid state memories, rotating discs of magnetic or optical media, and on magnetic tape.. While magnetic tape is characterized by simplicity of manufacture, high recording density, low cost and ease of use, it has one important limitation in that data must be recorded in a sequential path along the length of the tape. A relatively long time is required to locate the desired data for retrieval or editing because the tape may need to be wound over nearly its full length to the position of the data. Thus the access time is the major component of a retrieval parameter called latency. This access time is much longer than it is for solid state or rotating media. Magnetic tape is therefore, said to have a very high latency.
The high latency of magnetic tape is a persistent limitation that has only been partly overcome. It is a particular problem in the field of audio recording where it is frequently desired to access quickly the next selection for editing or playback.
Users accustomed to the rapid and versatile accessibility available with rotating media such as compact optical discs or magnetic floppy drives, would be more likely to employ magnetic tape to enable recording of favorite selections if the tape apparatus provided at least some of the random access capabilities of rotating media systems.
Previously, there have been several methods for accessing the data on magnetic tape. The manual cue and review method used with current audio and video recorders consists of manually operating the machine controls until the desired selection is heard or seen on a monitor, winding the tape to the desired point and then playing or recording from that point while keeping track of its position with a written or spoken record based on timing or tape length marking information. Some systems of this type employ rotation counters to keep track of tape position. This method is cumbersome, inefficient and not suited for digitally encoded information.
Other systems have automated some of these functions by combining marker signals on the tape, counter-detectors in the electronics and direct-entry of desired location information from a keyboard connected to control logic circuitry to enable the user to position the tape at the location of the desired data. An indicator also can be provided to display this location information to the user. Further, a separate index of data identity and data location also is needed for the user to position the tape for play, record or edit. Back-up or archival tape storage systems for computers and the more recent Digital Audio Tape systems are examples of this method that, in addition to being suited to digitally encoded data, offers more convenience in operation.
These systems, however, are limited because often, special information must be added during recording that reduces available recording capacity. The information is not available on pre-recorded tapes. The specific information would be specific to a particular hardware platform, thus it would not be interchangeable between similar hardware from other manufacturers.
Accordingly, what is needed is a method of programming audio tracks stored in a sequential medium, such as magnetic tape, that is compatible with other formats or platforms, or both, in the industry. The method should also provide editing features, which allows a user to edit the program.